Naruto Episode 101

“Gotta See! Gotta Know! Kakashi-Sensei’s True Face!”
In this episode based on a special omake, Naruto convinces Sakura and even Sasuke to help him see what Kakashi’s face looks like under his mask. Each one of their plans, such as buying him ramen to force him to remove his mask while he eats, fails in a comedic fashion. At the same time, they inadvertently and unknowingly thwart attempts by three ninja to kill Kakashi for goofy reasons. Finally, Kakashi agrees to take off his mask, revealing another slightly paler mask beneath it.
Info: Wikipedia